Exotic State Searches at the Spring-8: Observation of a Pentaquark State Θ Baryon
نویسنده
چکیده
A narrow resonance peak was observed at 1.54±0.01 GeV/c as an exotic baryon with strangeness S = +1 in the γ + n → K +K− + n reaction on C. The new state have a width smaller than 0.025 GeV/c and a Gaussian significance of 4.6σ. It can not be interpreted as three quark state and is consistent with the lightest member of an antidecuplet of baryons predicted by the chiral soliton model.
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At the PANIC conference in Osaka in October 2002, a collaboration working at SPring-8 announced a baryon state, the Θ(1540) with a decay mode Θ → nK. Assuming the decay is not Weak, that meant it had strangeness +1, and therefore was an exotic state (“exotic” in the sense that it is a baryon that cannot be a q state). It can be a ududs̄ state: a pentaquark. It has since been found at other labs ...
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